Periodic comet 96P/Maccholz is passing by the sun today deep inside the orbit of Mercury. At closest approach, the icy visitor from the outer solar system will be less than 12 million miles (0.13 AU) from the solar surface. Coronagraphs onboard the Solar and Heliospheric Observatory are monitoring the encounter: [go to: www.spaceweather.com]

"Discovered in 1986, Comet 96P/Machholz is a fascinating comet that has passed through SOHO coronagraph images four times now," says Karl Battams of the Naval Research Lab. "It's not a huge comet but it is very photogenic, and puts on quite a display with its beautiful dusty tail." In an essay posted on his web site, Battams explains why the comet is so fascinating. Many researchers suspect 96P/Machholz is not a native of our solar system; some chemical evidence suggests it came from another star. Also, 96P/Machholz appears to be dynamically related (that is, the comet's orbit is related) to a diverse collection of other objects in the solar system including asteroid 2003 EH1 and the Quadrantid, Southern Delta Aquariid, and daytime Arietid meteoroid streams. All of these things--the asteroid, the comet, and the meteoroids--might be fragments of a single "foreign" body that broke apart thousands of years ago. Comet 96P/Machholz will be visible in SOHO coronagraphs until July 17th. Battams believes the comet will reach a peak brightness of 2nd magnitude--not its best show. "But who knows," he says, "maybe Comet Machholz will do something completely and utterly unexpected like fragment into a swarm of Machholzlets." Join SOHO for a ringside seat. www.spaceweather.com